This proposal is designed to examine the effects of in vivo modification of normal tissue repair processes in the lung following a well defined acute injury such as that induced by cadmium chloride (CDCL2) aerosol inhalation or by a common food additive butylated hydroxytoluene (BHT); injuries which have been well documented in other laboratories. The objectives of the experiments detailed in this propoal are: 1) to examine the immediate effects of certain drugs on the histological repair process in the lung resulting from acute injury, 2) to determine the response of the injured lung to these drugs when administered at various interval after the onset of the acute damage, and 3) to attempt to correlate alterations in the acute repair process with the pathogenesis of certain chronic lung diseases. The drugs, Colchcine and Cycloheximide, have been chosen for use by reason of their well-documented actions on renewing cell populations as well as results obtained in preliminary studies by this investigator. These studies will involve primarily the histopathological evaluation of the modified injury, employing both light and electron microscopy. The injury will also be monitored by measuring the incorporation of labeled pecursors such as tritiated thymidine, L-Leucine L-Proline by liquid scintillation spectrometry and autoradiography.